Alzheimer's disease

Alzheimer's disease

Fast facts

Alzheimer's disease is a condition in which cells in the brain gradually degenerate and die.

Alzheimer's disease causes a person to gradually lose their ability to think clearly, remember, communicate and carry out routine tasks.

Unfortunately, there is no known cure for Alzheimer's disease, but its progression can be slowed by treatment. The earlier that treatment starts, the better the outcomes.

What is Alzheimer's disease?

Alzheimer's disease is a degenerative condition of the brain that causes problems with memory, thinking, language and behavior.

Alzheimer's disease is the most common form of dementia. Dementia is not a single condition, but a collection of symptoms that are caused by brain disorders.

Alzheimer's disease:

Is a leading cause of disability in older people (over 65 years of age), and;

Is more common in women than men.

Causes

Alzheimer's disease is caused by damage to brain cells called neurons. Neurons transmit the electrical nerve signals that carry information throughout the brain and body. The disease disrupts the neurons' ability to work properly, leading to loss of these signals and of information within the brain.

The human brain.

In Alzheimer's disease, the brain contains abnormal amounts of two proteins - amyloid and tau - as well as lower levels of the chemical messenger acetylcholine.

In people with Alzheimer's disease, fragments of the amyloid protein form sticky plaques, which build up outside the neurons. This can destroy neurons that produce acetylcholine. The tau protein has been found to build up inside the neurons.

It is thought that the accumulation of these proteins both inside and outside the neurons impairs the normal function of neurons, eventually leading to death of these brain cells.

Alzheimer's disease follows a gradual course; in its early stages, the brain is able to compensate for the damage to neurons. However, as the condition progresses, the damage spreads to other parts of the brain, and the symptoms become increasingly apparent.

Stages

The symptoms of Alzheimer's disease can be divided into three main stages:

Having Down syndrome. People with Down syndrome experience premature ageing and may be up to five times more likely to develop Alzheimer's disease.

Heart disease

A class of diseases that involves the dysfunction of the heart and/or the blood vessels.

Cholesterol

A type of fat produced by the body that is necessary for metabolism.

Diabetes

A metabolic disorder that is caused by problems with insulin secretion and regulation and which is characterized by high blood sugar levels. Also known as diabetes mellitus.

Types

The three main types of Alzheimer's disease can be described as follows:

Late-onset

This is the most common form, accounting for about 90% of cases. This type may or may not be inherited, and usually occurs in people over the age of 65 years.

Early-onset

This is a less common form, accounting for less than one in 10 (10%) of cases. This type may be linked to a specific genetic defect and usually occurs in people under the age of 65. People with Down syndrome are especially at risk of developing this type.

Familial

This is an extremely rare type, accounting for less than one in 100 (1%) of cases. This type is entirely inherited, and usually occurs in people under the age of 65 (often under the age of 50).

Signs and symptoms

Alzheimer's disease generally progresses slowly, so the symptoms may initially not be very noticeable. As the disease progresses, the symptoms become more noticeable and may interfere with daily life.

Some of the more common symptoms early on may include:

Short-term memory loss, which is persistent and frequent;

Language difficulties, such as struggling to find the right word or not being able to understand conversations;

Disorientation, even in places the person knows well;

Problems with carrying out familiar tasks;

Rapid and unpredictable changes in mood;

Decreased motivation or interest in hobbies, and;

Sleep changes, in the pattern or amount of sleep.

Methods for diagnosis

The early and correct diagnosis of Alzheimer's disease is important, as it:

Allows timely and appropriate treatment for other (curable) disorders that might be the cause of symptoms that mimic those of Alzheimer's disease;

Allows more time to plan for future needs, and;

Enables the possible use of medications that are most beneficial in earlier stages of Alzheimer's disease.

Patient history and cognitive testing

To diagnose Alzheimer's disease, your doctor may:

Obtain a complete patient history to help assess past and present health problems;

Obtain a complete family history, and;

Perform cognitive testing - to assess problem solving, counting skills, memory and attention span. This testing can help identify whether current memory and thinking abilities no longer match with a former level of function, and which areas of the brain may be affected.

Laboratory tests

Blood tests may be used to exclude other, potentially reversible, conditions that may be mimicking Alzheimer's disease.

Brain imaging

Brain imaging, including computerized tomography (CT) and magnetic resonance imaging (MRI) scans may be used in the diagnosis of Alzheimer's disease. These scans provide different kinds of images of the brain. The scans:

Help identify other causes of dementia including hemorrhages, tumors or stroke;

Distinguish between types of diseases causing the brain degeneration, and;

Establish a baseline of degeneration.

PET scans

A new imaging technique, a version of a positron emission tomography (PET) scan, has been developed that may identify areas and amounts of amyloid plaques formation. This test may help increase the accuracy of diagnosis but is not widely available as yet.

Computerized tomography

A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.

MRI

A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.

PET

During positron emission tomography (PET) scan, an injection with a radioactive label is administered and then combined with a computerized tomography (CT) scan to produce functional images.

Types of treatment

As there is currently no cure for Alzheimer's disease, the goals of treatment are to slow the progression of the disease, manage its symptoms, and set up a care plan to ensure that a person with Alzheimer's disease can continue to live a comfortable life.

Supportive treatment

Most people with Alzheimer's disease can remain in their homes as the disease progresses, as long as support is available. Carer support is crucial to the management of a comfortable life.

The first step in supportive treatment is to evaluate the self-care needs of the person with Alzheimer's disease. Then, simple changes can be made to the home environment to ensure that they are safe while at home, when driving or when out in the wider community.

Medication

Cholinesterase inhibitors

Restoring levels of the neurotransmitter acetylcholine is one of the strategies currently used in treating Alzheimer's disease. Medications such as donepezil, galantamine and rivastigmine improve cognition and slow the rate of functional decline. They show the most benefit if used in the earlier stages of disease.

A beneficial effect, if any, may be observed within 3-6 months of starting the treatment. Side effects of these medications may include stomach upset, vomiting, muscle cramps and fatigue.

N-methyl-D-aspartate receptor (NMDA) antagonist

Memantine belongs to a class of medications called NMDA antagonists. It does not slow the progression of Alzheimer's disease, but can improve symptoms for people with moderate to severe Alzheimer's disease. It may be used at the later stages of Alzheimer's disease.

Antidepressants

It is very common for people with Alzheimer's disease to experience depression. Depression can adversely affect cognitive function and add to the stress of carers.

There are many classes of antidepressants used to treat depression, but selective serotonin reuptake inhibitors (SSRIs) are usually the preferred treatment for depression associated with Alzheimer's disease. Sertraline, citalopram and escitalopram are some of the SSRIs considered as first-line treatment for depression associated with Alzheimer's disease.

Medication dosage might require adjustments over 1-2 months until the target dose has been reached.

As with most medications, antidepressants may have side effects. Some of the more common side effects include nausea, dizziness, fatigue and sexual dysfunction. There may be more serious side effects if they are taken in combination with other medications, herbal remedies, or alcohol.

There is a very rare risk of antidepressants causing or increasing suicidal thoughts. This risk is at its greatest during the first weeks of commencing treatment, or when the dosage is adjusted. Your doctor can advise you on ways to manage these changes.

Antipsychotics

People with Alzheimer's disease may experience anxiety, agitation and psychosis (hallucinations and delusions). Such symptoms may be treated with antipsychotic medication. However, the use of these medications is controversial, and may depend on the preferences of the treating doctor.

The antipsychotic drug risperidone has been shown to decrease the symptoms in some cases of Alzheimer's disease. However, there is some evidence that the use of antipsychotics may be associated with a higher risk of adverse outcomes. Common side effects of risperidone include agitation, anxiety, trembling, problems with urination, involuntary movements, weight gain and excessive thirst.

Sleep medications

People with Alzheimer's disease may experience sleeping difficulties (insomnia). Simple measures that can help manage insomnia include limiting naps during the daytime, getting daily exercise and using bright light therapy. If such measures do not help with insomnia, medication to help with sleep may be advised.

Acetylcholine

A compound found in both the central nervous system and the peripheral nervous system that is involved in the transmission of signals between nerves.

Anxiety

A feeling of tension, nervousness and dread about future events. It can trigger physical symptoms such as a rapid pulse or breathing difficulties.

Delusions

A mental state in which a person holds on to a belief despite clear evidence to the contrary.

Psychosis

An abnormal mental state characterized by a loss of contact with reality.

Hallucinations

A false perception of something that is not actually there. The perception can be visual or aural.

Potential complications

People with Alzheimer's disease do not usually die from the disease itself, but from its complications. Some of the more serious complications include:

Pneumonia - accidentally inhaling liquids and solids may increase the risk of aspiration pneumonia. Frequent bouts of pneumonia are more common in the late stages of Alzheimer's disease;

Urinary tract infections (UTIs) - the urinary incontinence associated with later stages of Alzheimer's disease may require the insertion of a urinary catheter. Urinary catheters are known to increase the risk of contracting UTIs. If left untreated, UTIs can lead to more serious complications, such as sepsis or multi-organ failure;

Falls - the impaired mobility and disorientation that comes at the later stages of Alzheimer's disease increases the likelihood of falls. Falls can cause complications such as fractures and head injury, and the lengthy immobilization required for recovery can lead to further complications such as blood clots (DVTs) and pneumonia;

Elder abuse - limited resources available to a carer may lead to neglect and isolation of the individual in their care, and;

Weight loss - people with Alzheimer's disease may experience considerable weight loss, which may lead to malnutrition, an impaired immune system, loss of muscle tone and the loss of independence.

Catheter

A thin, flexible tube inserted through a narrow opening into a body cavity for removing fluid.

Malnutrition

A condition in which a person does not receive the right amount of nutrients such as vitamins, minerals and proteins.

Prognosis

The natural course of Alzheimer's disease is a progressive decline to its terminal stages. Most cases progress over the course of 8-15 years. As the disease progresses, the symptoms become more apparent as do the self-care needs:

In its earlier stages, the moderate memory decline means that people with Alzheimer's disease require help carrying out routine tasks, taking their medications and dealing with financial matters, and;

In its later stages, the more severe impairment in memory, cognition and behavior means that people with Alzheimer's disease require full daily assistance with activities including bathing, eating and dressing.

Prevention

As the exact cause of Alzheimer's disease is currently unknown, there are no known ways to definitively prevent the condition, but there may be some ways of delaying the onset of dementia including:

Maintaining a high level of fitness and heart health, which may reduce your risk of developing Alzheimer's disease;

There is some evidence suggesting that the rates of Alzheimer's disease are lower in people who remain mentally and physically active; however, there is currently no evidence to support the theory that 'brain training' games are effective in reducing the onset of Alzheimer's disease.

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